Property Value

The ValidationKey property is used when enableViewStateMAC is true to create a message authentication code (MAC) to enable ASP.NET to determine whether view state has been tampered with. The ValidationKey property is also used to generate out-of-process, application-specific session IDs to ensure that session state variables are isolated between applications.

Use the "AutoGenerate" option to specify that ASP.NET generates a random key and stores it in the Local Security Authority. The "AutoGenerate" option is part of the default value.

If you add the "IsolateApps" modifier to the "AutoGenerate" ValidationKey value, ASP.NET generates a unique encrypted key for each application by using each application's application ID. "IsolateApps" is also part of the default value.

If you need to support configuration across a network of Web servers (a Web farm), set the ValidationKey property manually to ensure consistent configuration. For information about how to manually generate values for the DecryptionKey attribute, see How To: Configure MachineKey in ASP.NET 2.0.

This property is typically set declaratively in the validationKey attribute of the machineKey element of the Web.config file.